Custom titanium frame questions...

Discuss light weight issues concerning road bikes & parts.
Marin
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by Marin

The main reason for T47 for many builders seems to be for having more space for DI2 cabling. This reason will go away when Shimano goes wireless too.

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pdlpsher1
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by pdlpsher1

Marin wrote:The main reason for T47 for many builders seems to be for having more space for DI2 cabling. This reason will go away when Shimano goes wireless too.
As mentioned elsewhere, Shimano will go wireless when Sram’s wireless patent expires, or when Shimano developes an energy recovery system for both derailleurs. In other words this won’t happen anytime soon. Plus the lower range products like the Ultegra will likely stay as wired.

My Quarq DFour powermeter uses BB386 specs. I do see a trend of crank manufacturers moving away from BB30 to BB386.

My CK T47 cups weigh 97 grams. Slightly heavier than PF30 with nylon cups but much lighter than thread-together PF30 adapters like Praxis. One thing I really like about my CK T47 cups is the ability to service them via a grease injector. I just remove the cranks and insert the CK grease injector fitting. A few squirts of the blue marine grease and the bearings are as good as new. When serviced regularly I won’t have to replace BBs like I did so often with a PF30 BB.

Paragon Machine Works lists weights for frame parts. I’ll see if I can dig up the weights for T47 and BSA BB shells.


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pdlpsher1
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by pdlpsher1

I looked up the weights of the two BB shells on Paragon’s website. The BSA is lighter by 29g (55g vs 84g). The T47 will require slightly shorter frame tubing. So perhaps 10g. less tubing material for a T47. So a net diff of 19g. This is for titanium.


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Marin
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by Marin

pdlpsher1 wrote:
Wed Jun 06, 2018 9:14 am
I do see a trend of crank manufacturers moving away from BB30 to BB386.
SRAM at least is moving away from oversized shells, their current MTB cranks only come in 1 spindle size ("DUB") and can use BSA68 shells, and I'm sure their next road cranks will use the same standard.

https://www.sram.com/sram/mountain/prod ... m-brackets

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zank
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by zank

Calnago wrote:
Wed Jun 06, 2018 12:20 am
@zank... you’re a frame builder. What are your thoughts as to pros and cons of moving forward with T47 as a replacement to BSA for steel and Ti?
Biggest negative for me is the big 3 don't make BBs for it. I know that's true for other more prolific platforms too, but I don't use those either.

One positive of the wide variant is more room for 25.4 mm ti chainstays, but that's still manageable with BSA of course. I just cope the stay to the seat tube weld bead just like I do for aluminum bikes. The additional space for e-wires is nice, but I machine a relief inside my shells now for that.

I don't see the advantage to shell out for new taps and heatsinks. BSA all day for me.

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MayhemSWE
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by MayhemSWE

2lo8 wrote:
Tue Jun 05, 2018 11:41 pm
If SRAM ever updates Red to fit wide BB386, like they have for Force and lower, then it should be able to run on BSA.
They already have, sort of. It doesn't have the integrated carbon spider but consists of the exact same crankarms as used for the Red Quarq DZero just with a plain spider rather than power meter.

Personally though, I am very much expecting that whenever Sram releases their next generation of road groupsets both GXP and BB30 will go away in favor of a unified DUB standard as they've recently done for their mountain cranks.

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Calnago
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by Calnago

zank wrote:
Calnago wrote:
Wed Jun 06, 2018 12:20 am
@zank... you’re a frame builder. What are your thoughts as to pros and cons of moving forward with T47 as a replacement to BSA for steel and Ti?
Biggest negative for me is the big 3 don't make BBs for it. I know that's true for other more prolific platforms too, but I don't use those either.
Yes, that does bother me for sure as well. I like my Campy cups for Campy installs, etc.
“After market” stuff comes and goes. Tooling is not cheap for frame cutting tools for sure, but I don’t think that alone would stop me from going down that road if I was a framebuilder. But as a user... I suppose I’d have to really look at each situation case by case and decide what works best for that use.
Good discussion all. Thanks. “Standards” confuse me sometimes.
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pdlpsher1
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by pdlpsher1

Marin wrote:
pdlpsher1 wrote:
Wed Jun 06, 2018 9:14 am
I do see a trend of crank manufacturers moving away from BB30 to BB386.
SRAM at least is moving away from oversized shells, their current MTB cranks only come in 1 spindle size ("DUB") and can use BSA68 shells, and I'm sure their next road cranks will use the same standard.

https://www.sram.com/sram/mountain/prod ... m-brackets
Sram’s move to a smaller spindle is to address issues when one is trying to mate a 30mm spindle to a small diameter BB shell. They are not trying to get the frame manufactures to use a BSA BB shell. Large diameter BB shells will stay because they offer the most flexibility when it comes to crank compatibility.


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zank
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by zank

Large diameter BBs will stay because they offer the greatest profitability.

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zank
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by zank

Calnago wrote:
Wed Jun 06, 2018 1:36 pm

Tooling is not cheap for frame cutting tools for sure, but I don’t think that alone would stop me from going down that road if I was a framebuilder.
There just has not been a frame that I thought T47 would have solved a problem that I was faced with. That goes for titanium, aluminum, and steel. Most of my customers just want to use Shimano, Campagnolo, and SRAM BBs. I can't find a compelling reason to move away from BSA or even offer an alternative to it, and only a couple of people have even asked about it. It's all kinda meh. IMHO of course.

Marin
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by Marin

IMO large diameter PF was introduced because it seemed an easy solution for carbon frames, but it has kinda backfired with a lot of customer complains.

It's telling that Specialized is moving back to BSA, and it's not that hard to but BSA threads in carbon, and probably cheaper than a high number of warranty cases.

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Calnago
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by Calnago

Ok, I get that. I suppose in light of the huge popularity of internally routed electric systems however that the point about there being enough space to easily route the wires through the BB shell may be the biggest plus to larger diameter shells moving forward, if nothing else. I always appreciate a bike that’s easy to work on.
I think your “profitablity” of larger shells is not so much a function of the larger shells but more about the fact the big manufacturers don’t have to insert any alloy threaded sleeves into the majority of carbon shells, regardless of size, correct? Which of course adds another level of complexity and cost. The manufacturers did a good job of fooling the consumer into thinking pressfit bb’s were a good thing at the beginning, and here’s where we’ve ended up. It has however spawned a whole new cottage industry of aftermarket BB solutions to solve the problems associated with the pressfit applications as applied to bicycles. Is that good?... for the frame manufacturers it is for sure. For the end user... well, not so much. We’ve since learned to deal with the issues that plague pressfit solutions to the point I’m ok with it now. Still, threads work, are easy to deal with, and not so prone to damage from repeated removals and installs. I have however liked the wider shells from an overall ride experience. Both my Colnago C60 and my Koppenberg have wide shells and correspondingly wide downtubes attached to them. While there’s all kinds of other factors involved, it does seem to feel a bit more solid than say, my C59 with its 68mm BSA setup. Geez... I remember when the tubes on the C59 looked massive. Now they look like skinny steel tubes from the 70’s in comparison with what’s out there these days.
I still really appreciate a finely crafted steel or ti frame however. Kudos to you guys who take the time to do it right.
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zank
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by zank

Yes. You are correct. Profitability from the standpoint of making frames and assembling bicycles. Saving even a minute per bike can be huge cost savings. Pressing a BB will always be quicker. And making the frame without any type of threaded BB will be less expensive.

bremerradkurier
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by bremerradkurier

The larger diameter of the T47 standard would be kind of interesting to use for an oversized Ti axled square taper BB.

2lo8
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by 2lo8

MayhemSWE wrote:
Wed Jun 06, 2018 1:34 pm
They already have, sort of. It doesn't have the integrated carbon spider but consists of the exact same crankarms as used for the Red Quarq DZero just with a plain spider rather than power meter.

Personally though, I am very much expecting that whenever Sram releases their next generation of road groupsets both GXP and BB30 will go away in favor of a unified DUB standard as they've recently done for their mountain cranks.
If it's anything like Force and rival though, heavy, very. I think the big question for DUB is if the 1mm difference lets them get big enough bearings for BB86 and other 24mm specific PF variants. I know Rotor has a solution for BB86 30mm, but it's less than optimal. I don't know if DUB is the same way.
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by Weenie


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